Category: Paradox

StarGates Jump to FossCon — The Free & Open StarS Convention!

9/3/2017: I have just posted the slides from Fosscon on slideshare.  Comments, questions, problems, & buildable blueprints, all very welcome!

This coming Saturday I’ll be doing the latest revision of my StarGates talk at FossCon, the Free & Open StarS Convention!

(Pay no attention to those who assert this is the Free & Open Source Convention, that is a mere cover story.)

The convention is at International House in Philadelphia, starting at 9am, and is free.  As to my talk:

“Call them Stargates, Jumpgates, Fargates, Hypergates or just an invitation to every pest from the far reaches of the Galaxy to visit, they would be invaluable in helping mankind break free of this solar system.

Are StarGates only a convenient plot device — or could they actually be built? Accordingly to Einstein’s Theory of General Relavity, they are possible — at least in principle.

We will discuss how to glue black holes together to build a wormhole, how to avoid the dangers of spaghettification, radiation poisoning and paradox noise, and just what would it take to build one in practice.”

My talk’s at 1pm.  Hope to see you there!

And there I have you seen!  There was a nice turnout (in the South America room at International House) with a lot of questions.  We finished with a few minutes for additional questions, including my favorites:

What happens if you drag a wormhole through a wormhole?

I congratulated the questioner on the question & he just pointed at his young son sitting next, a lad clearly with a bright future as a scientist!

I had to admit I wasn’t sure, but I suspect it would be bad news for all concerned:  both wormholes, and any spaceships, space stations, or space-persons nearby!

How do you think this might actually be done?

I focused on wormholes because that is far & away the most popular of the approaches.  But if some sort of stargate were ever actually to come to fruition, I suspect a combination of the Einstein-Rosen-Podolsky (EPR) effect and the ideas behind the Krasnikov tube would be at work.  The EPR effect is the spooky-action-at-a-distance Einstein objected to; the Krasnikov tube is an idea of — curiously enough — Krasnikov for laying out a tube of warped spacetime behind your slower-than-light spacecraft.  You’d have to go slower-than-light while laying out the tube, but could use it for faster-than-light thereafter. And as I said in the talk, negative energy & vortices are pretty sure to be involved.



Invisibility, Anti-gravity, Ethics of Time Travel, & Balonium

I’ve just received my schedule for Philcon, being held in a bit over a week, November 8th thru 10th.  Curious collection of subjects, but looks like a lot of fun.  If you are in the Philly area, it would be great if you can come by!

Sat 1:00 PM in Crystal Ballroom Two (1 hour)


[Panelists: John Ashmead (mod)]

How do we hide a jet fighter, a tank, even a city from sight? For
millennia people have dreamt of invisibility rings, caps, & cloaks:
how close are we to Harry Potter territory? Progress in the last ten
years has been extraordinary, and, with some help from general
relativity, 3d printers, advanced photonics, and more than a pinch
of ingenuity, we can now bend, fold, & spindle light in ways
unimagined ten years ago
Sat 3:00 PM in Crystal Ballroom Two (1 hour)

[Panelists: John Ashmead (mod), Ed Bishop, Walter F. Cuirle, Jay

Both creating and negating gravity are very common tropes in science
fiction. It’s taken for granted in most Science Fiction that
spacecraft have normal gravity, although they do not spin. How this
is achieved is rarely discussed. Anti-gravity is nearly as common,
(and convenient for the plot).. Are either of these concepts
scientifically plausible? Could such a technology ever actually be


Sat 6:00 PM in Plaza II (Two) (1 hour)

[Panelists: John Ashmead (mod), Evelyn Leeper, Andrew C. Ely]

Everyone talks about killing Hitler in his crib, or stopping Booth
from shooting Lincoln. But if you could change the past, would you
Sat 7:00 PM in Plaza III (Three) (1 hour)

[Panelists: John Ashmead (mod), Darrell Schweitzer, John Monahan,
Sharon Lee]

From cavorite to kryptonite, science fiction fiction writers love to
add new elements to the periodic table. How do you create
convincing imaginary substances and what do you do with them

Quantum Mechanics, Reality, & You

I’ll be doing my talk “Quantum Mechanics, Reality, & You” tomorrow at Capclave, the DC SF Convention.  I have the latest slides up on slideshare.

Enjoyed putting the talk together.  I go thru the interpretations of quantum mechanics — some spectacularly silly — and then argue that quantum mechanics is real, you & I — not so much.  🙂

Also doing panels at Capclave on Hot Steamed Punk, Practical Uses of Faster-Than-Light Travel, Choose Your Own Apocalypse, & Great Cthulhu:  Threat or Menace?


Temporal Paradoxes Talk Done: World Safe for Grandfathers

Had a very good time at NASA’s Goddard Space Center doing my talk Temporal Paradoxes.  Nice crowd; lots of good questions.  NASA’s audio-visual support was first rate, as you would expect, and the talk should be up on their site in a bit.  I’ll post a link here when that happens.

I’d like to thank Brent Warner & his colleagues for their warm welcome & all the feedback during the talk.  Brent tells me he particularly liked the quote from an Astounding Science Fiction reader (1933):

“Why pick on grandfather? It seems that the only way to prove that time travel is impossible is to cite a case of killing one’s own grandfather. This incessant murdering of harmless ancestors must stop. Let’s see some wide-awake fan make up some other method of disproving the theory”*

As I say in the talk, if the current literature is on target, the grandfather & other paradoxes are cancelled out by interference by the time machine’s wave function with itself.

Brent & his NASA colleagues were kind enough to provide lunch & a fascinating tool of the facilities:  they manage the Hubble & are working on the James Webb.  Huge rooms with vast devices for subjecting equipment to high G’s, vacuum, heat, noise, vibration, & every other insult that it will need to be able to withstand during launch or in space:  gives one a real sense of just how hard it is to get this stuff to work!

*as quoted by Paul Nahin in his Time Machines: time travel in physics, metaphysics, and science fiction

Temporal Paradoxes Talk Online

I had a lot of fun putting my NASA talk Temporal Paradoxes together.  The feedback I got from the assembled multitude at the Radnor Library last week was extremely helpful, leading to a near complete rework of the talk, in the interests of making it clearer.   Thanks!

The pdf & keynote versions are now online.

Practice Run Thru on Temporal Paradox Talk

I’m doing a practice run thru on my Temporal Paradoxes talk at NASA.

The run thru will be at the Winsor room at the Radnor Memorial Library on March 12 at 2pm.  This is a few hundred feet from the main intersection in Wayne, PA.

The talk is basically the Physics Of Paradox talk, but more focused on the physics than the science fiction (tho in this area it can be hard to tell them apart) & with animations.

Since this is a complete redo of the talk, I’m hoping to get feedback on timing & clarity & focus & such like!

Please come!  And criticize!


— John Ashmead

Temporal Paradoxes Talk at NASA

I’ve been asked to do a talk, Temporal Paradoxes, at NASA.  This will be on the 21st of this month, at 3:30pm.  This is a NASA-fied version of my previous Physics of Paradox talk, meaning more animations & less science fiction, and perhaps a few equations in a grayish font.  Abstract:

ABSTRACT — Einstein’s general relativity is the leading theory of gravity. Simple and elegant, it has passed all available experimental tests including: deflection of light by gravity, precession of orbital apsides, gravitational time dilation (used in GPS), and frame-dragging.

However, general relativity makes a number of counter-intuitive predictions. In particular, trajectories looping around massive, rapidly rotating stars or passing through a wormhole can close on themselves in time, creating closed timelike curves (CTCs).

This creates the possibility of “grandfather” and “bootstrap” paradoxes. Recent work by Greenberger & Svozil, and others, however, questions this conclusion. That work suggests that when quantum mechanical effects are included, the paradoxes become self-canceling, eliminated by destructive interference within the wave function. If the paradoxes are self-canceling, then closed time-like curves are possible. If they are possible, can we create or detect them?

Several authors have suggested that we look for evanescent wormholes with the Large Hadron Collider. If we find them, we may be at the edge of temporal paradox. While the only safe prediction in this area is that there are no safe predictions, we look at the implications of this for general relativity, quantum mechanics, & causality.

Reality versus free will, escaping the Holodeck, are the laws of physics “more guidelines than rules”?, and more!

I’m doing five panels and my Physics of Paradox talk at the Philadelphia Science Fiction Convention, starting in a few hours.

Quite a lot of fun subjects for my panels:  Augmented Reality (for those who can’t get enough reality), Time Travel & Free Will, Are the Laws of Physics Laws (or really more just Guidelines?), Is the Universe a Hologram (& can I leave the Holodeck?), my Physics of Paradox talk in its final & perfected version, & What Came Before the Big Bang (& are we in trouble with whatever it is?)

[I’ve augmented the reality of the Physics of Paradox slides by adding the spoken text to them:  see the Keynote (for Mac users), PowerPoint (for PC users), and  annotated pdf version.]

My complete schedule is:

Fri 10:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: John Ashmead (mod), Earl Bennett, Rock Robertson, Bud Sparhawk]
We’ve all heard about virtual reality and the potential it holds for gaming, learning, medicine etc., but augmented reality, while less well-known, is more likely to have a major effect on everyday life. Imagine wearing a pair of glasses while driving that produce flashing arrows to indicate your turns, or looking at a city street through your cell phone screen and seeing each building labeled by name and type of business. Learn what’s happening now and what we can expect in the future.
Sat 11:00 AM in Plaza VII (Seven) (1 hour)
[Panelists: John Ashmead (mod), Michael F. Flynn, John Grant, Helen Collins, Lawrence Kramer]
Suppose that  three weeks in the future I come back and sit on this panel,does this not imply that nothing can happen in the future toprevent me from getting in a time machine and coming back? Does this mean that time travel implies that the future is pre-determined?
Sat 12:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: Paul Halpern (mod), John Ashmead, Jay Wile, Tony Rothman]
Are the laws of nature really the same across all space and time? No principal is more fundamental to physics than the idea that the laws of nature remain the same at all times and in all places. Much we believe to be true about the universe depends upon this concept. However, new observations have revealed anomalies that suggest that such physical laws as the fine structure constant and the speed of light may actually have changed over time. Will we soon have to rethink our ideas about physics and cosmology
Sat 2:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: Paul Halpern (mod), John Ashmead, Jay Wile, Tony Rothman]
Is the universe a hologram? One of the strangest ideas to come out of modern physics is the holographic principal, which speculates that the universe may be a multi-dimensional projection of information encoded (in Planck length-sized  squares, each containing one bit of information) on a two-dimensional boundary called the cosmological horizon. A new experiment searching for gravity waves may have accidentally found evidence for this theory that was predicted by supporters.
Sat 3:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: John Ashmead (mod)]
There is nothing in modern physics to rule out time travel, save paradox.  And — thanks to quantum mechanics — it seems any potential paradoxes would be self-canceling.  Therefore the only thing standing between us and time travel is not knowing how to go about it, exactly.  But several recent papers have proposed ways to use the Large Hadron Collider at CERN to create particle loops that
go backwards in time.  Now what?
Sat 5:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: John Ashmead (mod), Paul Halpern, Eric Kotani, Tony Rothman]
Was there a time before the beginning? As incredible as it seems, new discoveries have given scientists clues about what may have existed prior to the beginning of our universe. Scientists at the University of Pennsylvania have developed a mathematical model that traces through the Big Bang to a shrinking universe that exhibits physics similar to ours. Measurements of the Cosmic Microwave
Background radiation reveal an imprint from the earliest stages of the universe may also shed light on what came before. The following links are offered as jumping off points to potential panelists who would like to investigate this topic:

The Physics of Paradox — Followup

Gave the Physics of Paradox talk at the Library of Congress Thursday (10/21/2010) & then again at Capclave Saturday (10/23/2010).   Good audiences both times, lots of good questions.  At Capclave talk was standing room only & Brent Warner, from the Goddard Space Center has asked if I would be interested in doing it there this spring.

I made some changes to the talk over the weekend, in response to audience feedback & further reflection.  The latest version is now up as Keynote (for Mac users), PowerPoint (for PC users), PDF in slides-only and also annotated forms.

I’d like to thank Dick Ladson, Walt Mankowski, Bruce Bloom, Shelley Handen, Ed & Marguerite Rutkowski, & of course Ferne Welch for their feedback at the dry run, which improved it immensely.  And I would like to thank Nathan Evans of the Library of Congress & Colleen Cahill of Capclave (& as it happens the Library of Congress) for having me.  Lots of fun!

Time and quantum mechanics at the Chestnut Hill Book Festival

Spoke at noon yesterday (July 10th, 2010) at the Chestnut Hill Book Festival; in spite of heavy rain a nice crowd.
This was my Balticon Time & Quantum Mechanics talk, adjusted for a general (rather than a science fictional) audience.  I covered over a hundred years of physics in less than an hour — a lot — but the audience survived & even seemed to prosper, asking some good questions!
I’ve uploaded the power point and keynote versions of the talk so you can see the animations of the double slit experiment, if you have power point and/or keynote.  You may have to tell your browser how to handle .ppt and/or .key files, for all parts to work with maximum smoothness. I’ve also uploaded the pdf and html versions.
The references — several asked after them — are on slide 36.  Enjoy!
I’d like to thank Oz Fontecchio for organizing this, Ferne Welch for moral & practical support, Bob Rossberg (sp?) for critical help on the AV, & the Chestnut Hill Book Festival for providing the venue!

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